Simple COMSOL Question
 

I am new to CFD and just exploring what COMSOL can do. I am trying to simulate a pressure driven flow through a tube in 2D. This is a simple problem to solve analytically but I cannot obtain any numeric results. The only way to obtain a solution is to apply some sort of inlet velocity (using laminar inflow). I feel I may have some issues with whether or not I should be using a reference pressure, what the initial value for pressure I should use, and which type of boundary condition to apply. The example I am trying to simulate is a 10 cm diameter tube, 1 m long, water as the fluid, a pressure of 100 kPa on the inlet and 80 kPa on the outlet. I feel I am just doing something quite basic incorrectly which is preventing me from obtaining an solution. Thanks for your help.